The infant voices (musical/war-like tools) are sufficient to 1) establish strength and 2) silence/still foe and avenger. Hence, Psalm 8 teaches that the music of God is composed of every covenant member. Not that adult voices do not frighten Yahweh’s enemies, but that even the infant voices cause the same affect. The seed and the tree are kingdom (Matthew 13). The seed grows into kingdom maturity, but the seed is already kingdom.

Naturally, this is also a messianic passage. The God/Man was the ultimate babe who silenced every foe and avenger.